EFFECTS OF SURFACTANTS ON CALCIUM PENETRATION OF CUTICLES ISOLATED FROM APPLE FRUIT

Transport of Ca-45(2+) across enzymically isolated cuticles from apple fruit (Malus domestica Borkh. cultivar 'Granny Smith') was followed in an apparatus where the cuticle was clamped between two solutions, and the appearance of Ca-45(2+) recorded in the sampling solution. Ca-45(2+) transport from the outer to the inner surface of the cuticle could be increased by some surfactants when they were exposed to the inner, non-waxy surface. Addition of Armoblen T25 and Tween 20 increased the transport rate, Agral LN had little effect and Armoblen NPX inhibited transport. When the surfactants were applied to the outer surface there was little effect, except with Armoblen NPX where transport declined. As the cuticles did not contain any cracks or functional lenticels these results suggest that the surfactants increased Ca2+ transport by altering the permeability of the cuticle as a result of having direct access to the cutin and polysaccharide matrix.